AITAH for laughing when my the family of the daughter of my mom's friend thanked God instead of my boyfriend?

So, my (31F) mother has this friend who has a daughter, my mom asked me to go to visit the daughter and attend the dinner on behalf of our family. There was the daughter, her husband, their kids, her parents, parents in-laws and her sister in law. My boyfriend (30M) was invited too.

The daughter and her family and in laws are Christian, so before eating they asked everyone to pray. My boyfriend isn't religious and religion wasn't a part of his upbringing in the slightest, not in school or at home. Even when he see something like (John 36:4 - random numbers ofc ) he doesn't get it right away, you have to tell him that this is related to the bible.

We didn't hold hands or anything but the father in law thanked Jesus for the food. My boyfriend's name is Joseph so he thought that they mixed Joseph with Jesus so he said "Oh thank you".

As I said, religion wasn't part of him upbringing or education so it's normal that religion doesn't pop up his mind immediately, in addition, he had an art teacher called Jesus, so it isn't like he only heard of the name Jesus in religious contexts.

Anyways, they all looked at him and he looked back confused. I laughed and said "And thank you Joseph". The father said "Are you mocking us?". Seconds later he realized it and quietly said "Oh, damn I'm dumb". He apologised and tried explain it but it was awkward.

The parents and sister in law didn't look convinced. They thought Joseph was mocking them and that I was mocking them even more when I laughed. It was awkward overall. The daughter is fine though, she looked like she just wanted to eat.

Joseph did a small mistake and apologized, but since the talk wasn't directed toward me I didn't apologise for laughing. Was I rude for laughing it off? Or was it just the in laws?

Edit: he brought the food that's why he thought that they were thanking him.